The present invention relates to methods and apparatus for observing flowable material, e.g., observing a change in one in one or more parameters in a flowable material in a vessel, using ultrasound, and particularly relates to monitoring one or more parameters in the flowable material in a vessel using ultrasound, e.g., to determine the presence and/or formation of agglomerates in the flowable material and/or to monitor fermentation.
Observation of changes in the properties of a flowable material in a vessel or monitoring of a process occurring within a vessel are important in a large number of industries. Examples include measurement of changes of the properties of a flowable mixture in a fermentation tank, or monitoring of the progress of a reaction in a pharmaceutical synthesis vessel.
Properties of the flowable materials in vessels have been monitored by using fixed mechanical sensors inside the vessel which measure individual parameters. Alternatively, ultraviolet (UV) spectral measuring equipment may be arranged on the outside of the vessel with a window in the wall of the vessel through which measurements can be made. In either of these cases, specially designed or adapted vessels are required to accept sensor units inside them or with windows or apertures in their walls through which measurements can be made.
It is also known to measure the level of a liquid in a vessel by putting an ultrasound sensor facing down towards the top surface of the liquid and measuring the time of flight (correcting for temperature) of an ultrasound pulse returning after contacting the surface of the liquid.
However, these approaches have suffered from a number of drawbacks, e.g., some are not applicable to certain classes of flowable material, and same provide inaccurate and/or delayed results, requiring a labor intensive effort, and/or requiring specifically designed equipment.